Alternating current line fault determination method and system based on double-end transient quantity

Abstract

The invention relates to an alternating current line fault determination method and system based on a double-end transient state quantity, and belongs to power system line protection, and the method comprises the following steps: obtaining a first fault current additional component in a preset time period when a fault is detected at an M side of a protected line, and a second fault current additional component within a preset time period when the N side of the protected line detects a fault; acquiring a frequency domain current ratio of the first fault current additional component to the second fault current additional component; calculating the frequency spectrum fluctuation variance of the frequency domain current ratio; and determining whether the fault belongs to the internal fault of the protected line according to the frequency spectrum fluctuation variance. According to the method, fault identification based on instantaneous change of a system power supply and a short-circuit path after the fault occurs is realized, and the requirement of relay protection of a novel power system is met.

Description

technical field [0001] The invention relates to the technical field of power system line protection, in particular to a method and system for determining AC line faults based on double-terminal transients. Background technique [0002] The new power system is a power system with new energy as the main body. Since the new power system has a high proportion of new energy power sources and a high proportion of power electronic equipment, the electrical characteristics of the power frequency of the system have also changed. At present, the power system is still configured with line protection schemes in a conventional way, and the traditional protection principles have begun to show poor adaptability. The problem. The traditional power frequency protection considers that the grid power supply voltage and short-circuit impedance remain constant at the moment of the fault, while the rapid adjustment of the control mode and topology structure of power electronic devices, and the r...

AI Technical Summary

Problems solved by technology

Because the new power system has a high proportion of new energy power sources and high proportion of power electronic equipment, the electrical characteristics of the system fault power frequency have also changed. At present, the power system still configures line protection schemes in a conventional way, and traditional protection principles begin to show poor adaptability. The problem

The traditional power frequency protection believes that the grid power supply voltage and short-circuit impedance remain constant at the moment of a fault, but the rapid adjustment of the control mode and topology of power electronic devices, the rapid change of the new energy power supply operation structure and control strategy, make the system power supply and short-circuit resistance after the fault occurs. The path changes instantaneously, resulting in the traditional protection based on power frequency electrical quantities. In this scenario, the fault cannot be detected, so it cannot fully meet the requirements of the new power system relay protection.

Images